Echoes in Time by Andre Norton and Sherwood Smith is the continuation of Norton's old Time Traders storyline, now updated to the post-Soviet era. Strange things are afoot on the world of Dominium, where many centuries ago there was a city inhabited by many races living together. But the Russian team sent there to investigate has been lost, and a combined Russian-American team must now go to investigate. To make things even more complex, the team discovered a perfect portrait of one of the African time travellers in the ruins of the city in later centuries. Since this means that she has already visited this world, she must be included in this mission in order to prevent history from going off its tracks.

After the long trip via the mysterious bubble-ship left by an ancient race whose technology humans do not fully understand, the team arrives and travels into the past to work themselves into this strange society. They soon note a troublesome pollen that permeates the atmosphere of this world and seems to be causing allergic reactions in spite of their best medical efforts. However, they really don't have time to worry about that overmuch, since the delicate process of figuring out this complex society is devouring all their time and attention.

Meanwhile the African member of the team, Saba, has been drawn into the inner circle and is being taught the hidden secrets, in particular dealing with a supposed timeless entity who inhabits this world. However, she is suffering from some illness that is rapidly eroding her health. Slowly the team unravels the secrets of this world, and of the mysterious entity that rules it from the shadows of time.